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Abstract: As interest in nanomaterials and nanotechnology continues to grow, so does the need for more efficient and economical synthesis methods to keep up with the demand. Nanomaterials, having at least one critical dimension measuring less than 100 nm, could exhibit unique properties compared to their bulk counterparts. These unique properties, which include electrical, optical, thermal, mechanical, and magnetic properties, influence the integration and utilization of these materials into devices and applications. The applications for nanomaterials are seemingly endless as they have functions in energy, biomedical, environmental, and many more. Working to develop different morphologies and sizes of nanomaterials will further help expand its utility. With the use of advanced characterization techniques such as in situ transmission electron microscopy (TEM), real time studies on the effects of external forces on nanomaterials are possible under controlled environments. This will give insight on how nanomaterials will perform in real world applications and will allow for the development of superior nanomaterials and applications.

The three sections of this talk will focus on the solid-state synthesis of crystalline nanomaterials with specific morphology as well as the real time observation of thermal treatments on the stability and degradation of nanomaterials via in situ TEM. The first two sections concentrate on the hydrothermal and chemical vapor deposition synthesis and materials characterization of nanomaterials with magnetic and semiconductor properties. The third section focuses on the in situ observation of the reaction of nanomaterial and nano-interfaces as they are subjected to increased temperatures within the TEM. The works presented here show the versatility of nanomaterial syntheses and demonstrate the application of real time advanced electron microscopy techniques to further study the structure-property relationships of nanomaterials.

Graduate Student Profile

Abstract: In recent years, organic-inorganic metal halide perovskites (HP) have garnered tremendous attention in photovoltaic research. This attention is attributed to their low cost and excellent optoelectronic properties, including large absorption coefficients, tunable bandgaps, long charge carrier diffusion lengths, and low trap state densities. Inverted p-i-n architecture perovskite solar cells (PSCs) are of intense interest and are generally regarded as more amenable to low-temperature solution processing. Nevertheless, the development of inverted PSCs is lagging the conventional architecture devices. Imperfect energy level alignments and charge carrier recombination, especially at the interface between perovskite and electron transport layers (ETLs), are two main factors suppressing the power conversion in inverted PSCs.

Organic semiconductors (OSCs), including π-conjugated polymers and small molecules, display distinct advantages in terms of low-cost, lightweight, wide variety, easy solution-processed manufacturing as well as excellent mechanical flexibility. The molecule design produces numerous organic semiconductors with desired properties in application of various advanced organic electronics devices. However, the performance of OSCs-based devices is left behind their inorganic counterparts due to the lower carrier density and mobility. Molecular doping which provides a route to significantly enhance the electric properties, attracts attentions progressively.

Tuo Liu’s work during his PhD focused on the applications of photoelectron spectroscopies on the studies of perovskite solar cells and organic semiconductor-based electronics. The first work carried out how the surface ligands impact interfacial energetics and charge carrier dynamics at methylammonium lead iodide (MAPbI₃)/C₆₀ interfaces. The frontier electronic energy levels at perovskite/C₆₀ interface are directly probed by ultraviolet photoelectron spectroscopy (UPS) and low energy inverse photoelectron spectroscopy (LEIPS), providing evidence of interfacial energetics reconstruction caused by surface ligands with different dipoles. Ultrafast absorption/reflectance spectroscopies and transient photovoltage/photocurrent are utilized in comprehensively picturing the charge dynamics in films and devices. The following work reports the doping mechanism in the photoactivated p-doping of hole-transporting material (HTM) to enhance hole extraction for perovskite/textured silicon tandem solar cells, making the device performance less sensitive to the variation of hole transport layer thickness. Last several collaborations works are based on the doping behaviors in different doped organic semiconductors, with applications in organic solar cells and thermoelectrics.

Graduate Student Profile

Abstract: Development of a new kind of drug delivery system (DDS) that could efficiently deliver therapeutics to the cell of interest would allow us to accomplish cell-specific drug delivery while eliminating systemic toxicity. Although nanocarriers including endogenously released extracellular vesicles (EEVs), liposomes, and small molecules seem to be promising drug delivery systems,  biological challenges persist for their use in clinical applications. Here, we demonstrate nanovesicles engineered by fragmenting cellular membranes  can be exploited as versatile DDSs for therapeutics delivery as well as immunomodulatory functions. Cell-engineered vesicles were produced by cavitating cells using nitrogen gas at high pressure followed by serial centrifugation. Cell-engineered vesicles (CEVs) are smaller in size, can be generated in high yields, easily loaded with both lipophilic as well as hydrophilic cargo, and exhibit cell-targeting specificity both in vitro as well as in in vivo.

Cell-engineered vesicles generated from immune cells offer additional advantages as immunomodulatory therapeutic agents. Herein, we demonstrate that macrophage-engineered vesicles (MEVs) generated from macrophages, immune effector cells, can modulate the physiological states of immune cells including macrophages and microglia. While MEVs generated from anti-inflammatory (M2) macrophages re-program neuro-toxic pro-inflammatory (M1) macrophages towards M2-like phenotype, MEVs generated from M1 macrophages re-polarize M2  macrophages towards an anti-tumor M1-like phenotype. In addition, in vitro and in vivo delivery of cargo is facilitated by the ability of these vesicles to selectively target the same cell type from which they originated.

Programming cell-engineered nanovesicles through the targeted over-expression of specific membrane-bound ligands transforms them into a more potent immunomodulatory as well as therapeutic delivery platform. We tailored membrane-derived nanovesicles to have unique immunomodulatory features, including the potential to regulate immune cell polarization in both directions. These programmable nanovesicles adorned with certain membrane-bound ligands are capable of targeting particular cell types. Using programmed nanovesicles produced from macrophages enhances immune cell reprogramming to both proinflammatory and anti-inflammatory cells. Additionally, the incorporation of cancer cell-targeting moieties into the vesicle membrane enhanced the transport and absorption of therapeutically loaded nanovesicles, hence increasing their effectiveness.

Graduate Student Profile

Dr. Ferguson will be presenting a broad overview of her research portfolio and Dr.'s. Glasscott and Kimball will briefly discuss their specific research. The presentation will shed light on an alternative career path and should be of interest to a broad array of students. 

Abstract: Oxygen reduction reaction (ORR) and conversion of bicarbonate into value-added chemicals are two significant electrochemical processes for energy storage and conversion. ORR is an important electrochemical reaction in fuel cells and metal air batteries that provides power conversion and storage capacity, respectively, for portable electronics and electric vehicles. However, the performance of catalysts (e.g., platinum-based) is critically limited by slow kinetics, inefficient four-electron pathway and surface deactivation. This limited performance of platinum-based catalysts, the scarcity of platinum, and vulnerable supply chains for critical minerals require the development of alternative electrocatalysts now more than ever. 

Carbon-based materials possess several key properties that are beneficial for catalytic applications such as high electric conductivity, large surface area, inert electrode surface and low cost. Catalytic activity of carbon-based electrode can be promoted by tailoring surface and structure through the incorporation of heteroatom dopants. This work focus on synthesis of electrocatalysts and their surface modification to achieve effective ORR performance in alkaline media. The ORR performance of nitrogen (N) and boron (B) co-doped carbon nano onions (CNOs). In this work annealing temperature was found a crucial factor in the synergistic benefit of N and B towards ORR. Furthermore, this research was extended to discuss the impacts of nitrogen heteroatom and copper nanoparticles on ORR performance.

Moreover, electrocatalytic carbon dioxide (CO2) reduction (CO2RR) in a membrane electrode assembly was investigated. Atmospheric CO2 has significantly increased in last two decades. Since CO2 is a primary greenhouse gas emitted on earth, it is imperative to suppress the concentration of emitted CO2. While the regulation of CO2 emissions is critical, CO2 capture and storage (CCS), and biological, chemical, and electrochemical conversions are promising approaches to reduce atmospheric CO2 concentration. In electrochemical conversion, a common method employs the feed of high-purity compressed CO2 gas into an electrolyzer. This method, however, is not economically viable because it requires the release and/or pressurization of CO2 from captured CO2 solution, which are energy-intensive. To resolve this issue, aqueous carbonate/bicarbonate (CO32-/HCO3-) transported from upstream carbon capture process can be directly fed into an electrolyzer. We demonstrate that a cationic exchange membrane coated with a thin copper film can efficiently convert bicarbonate to C1-C2 products such as formic acid and acetic acid. Both liquid and gas products were quantified by using proton nuclear magnetic resonance (H1 NMR) and gas chromatography, respectively. 

The studies herein highlight the importance of structure modification of catalysts, surface chemistry, and membrane-electrode interface to improve the efficiency and selectivity of ORR and CO2RR processes. 

 

Student Profile

Abstract: Smoking and tobacco use (STU) is a major global health problem and worldwide more than six million people die due to tobacco related diseases each year. Although majority of smokers try to quit smoking several times in their life, traditional therapeutic approaches, which focus only on neuronal cells, have a very low success rate.   Understanding the effect of nicotine on glial cells, synaptic communication and blood vasculature in the brain can provide further insights on the neurobiology of substance abuse and can potentially help to design better therapeutic approaches. Glial cells are nonexcitable cells in the brain which do not generate action potentials. Recently many additional functions of glial cells have been discovered which have challenged the traditional neuro-centric view in neuroscience. Astrocytes are major glial cells which regulate synapse, maintain homeostasis, maintain blood brain barrier, and regulate blood flow. Processes from one astrocyte can interact with as many as 10,000 synapses. Astrocyte also couple with blood vasculature and play key role in supply of oxygen and nutrients to the brain. In these studies, we investigated the effect of nicotine on astrocyte morphology and functional activity. By using tissue clearing and time lapse fluorescence imaging approaches, we showed nicotine induces morphological rearrangement of astrocytic processes mediated via nicotinic receptors. We also studied the functional consequences of astrocytic rearrangement in the brain in terms of cytokine release, cell viability and calcium activity. To further characterize the subcellular astrocyte calcium activity in physiological and pathological conditions, we developed a GCaMP based genetic probe by targeting the endoplasmic reticulum (ER) in astrocytes. This probe was shown to measure astrocyte specific calcium activity in the periphery of the ER in cell culture and in vivo. As astrocytic processes form intricated networks with synapses, we also developed a single molecule fluorescence imaging approach to characterize synaptic nicotinic receptors and observed nicotine-induced stoichiometric shift in post synaptic nicotinic receptors in the brain. By using pH sensitive super ecliptic pHluorin (SEP) probe, we showed nicotine also alters the trafficking of nicotinic receptors from the ER to the plasma membrane.  In summary, we developed and applied several fluorescence microscopy-based tools to study the astrocyte activity in various physiological conditions. Nicotine was shown to alter the morphological and functional activity of astrocytes through nicotinic receptor activation. We also developed a genetic probe to image calcium activity in astrocytic processes. Our studies of synaptic nicotinic receptors showed nicotine alters their stoichiometry from low affinity subtype to high affinity subtype. These studies highlight the importance of fluorescence-based approach to study tobacco use disorder and provide further insights on nicotinic receptor pharmacology and astrocyte biology.

Graduate Student Profile

Chamikara Karunasena

Graduate Student Profile

Abstract: The immense synthetic design space and material versatility have driven the exploration and development of organic semiconductors (OSC) over several decades. While many OSC designs focus on the chemistries of the molecular or polymer building blocks, a priori, multiscale control over the solid-state morphology is required for effective application of the active layer in a given technology. However, molecular assembly during solid-state formation is a complex function interconnecting the building block chemistry and the processing environment. Insufficient knowledge as to the how these aspects engage, especially at the atomistic and molecular scales, have so far limited the ability to predict OSC solid-state morphology, leaving Edisonian approaches as the stalwart methods. Therefore, through multiscale simulations combining atomistic quantum scale modeling and modern advanced sampling molecular dynamics (MD), we aim to establish first principles understanding required to synthetically regulate solid-state morphology of organic semiconductors (OSC) as a function of molecular chemistry and processing. In turn we try to understand the deceivingly simple yet complex mechanisms behind molecular aggregation and crystallization of OSC. Simultaneously, we develop semi-to-fully automated high-throughput schemes to automate the complex and labor-intensive analyses to generate data based on various crystal structures in different crystallization environments. Ultimately, we aim to bridge molecular-scale information revealed on solid-state physical organization, understood in the context of chromophore chemistry and the molecular environment, with the macro scale properties to uncover useful guidelines for rational design and morphology regulation of OSC systems.

This lecture series commemorates Professor Dawson's leadership in the Department and features speakers noted for the quality, depth and breadth of their research.

Jeffrey Moore received his B.S. in chemistry (1984) and Ph.D. in materials science and engineering with Samuel Stupp (1989), both from the University of Illinois. He then went to Caltech as a National Science Foundation Postdoctoral Fellow working with Robert Grubbs. In 1990, he joined the faculty at the University of Michigan in Ann Arbor and in 1993 returned to the University of Illinois, where he was Professor of ����vlog�ٷ����, as well as a Professor of Materials Science & Engineering until 2022 and was also selected as the Stanley O. Ikenberry Endowed Chair in 2018. Jeff is a member of the National Academy of Sciences and a fellow of the American Academy of Arts & Sciences, the American Association for the Advancement of Science and the American Chemical Society (ACS); he has received the Campus Award for Excellence in Undergraduate Teaching and has been recognized as a “Faculty Ranked Excellent by their Students.”

For 14 years he served as an associate editor for the Journal of American Chemical Society. In 2014, he was selected as a Howard Hughes Medical Institute Professor and in 2016 was chosen as the recipient for the ACS Edward Leete Award in Organic ����vlog�ٷ����. He received the Royal Society of ����vlog�ٷ����’s Materials ����vlog�ٷ���� Division 2018 Stephanie L. Kwolek Award and was part of a team that was honored with the Secretary of Energy Honor Award, Achievement Award the same year. Jeff was also awarded the 2019 National Award in Polymer ����vlog�ٷ���� by the American Chemical Society. He has published over 400 articles covering topics from technology in the classroom to self-healing polymers, mechanoresponsive materials and shape-persistent macrocycles. He served as the Director of the Beckman Institute for Advanced Science and Technology at the University of Illinois from 2017-2022. In this role, he received the 2021 Executive Officer Distinguished Leadership Award from the UIUC Campus.

"Polymeric Materials for Lifecycle Control"

In this talk I will discuss the molecular design of organic structural materials that mimic living systems’ abilities to protect, report, heal and even regenerate themselves in response to damage, with the goal of increasing lifetime, safety and sustainability of many manufactured items. I will emphasize recent developments in frontal ring-opening metathesis polymerization (FROMP)to manufacture composites with minimal energy consumption. The talk will conclude by introducing the idea of morphogenic manufacturing in which we aim to achieve symmetry breaking in neat polymerization reactions through a coupled reaction-diffuse process; the longterm vision is self-patterned form and function in synthetic materials.

References:

1. Patrick, J.F.; Robb, M.J.; Sottos, N.R.; Moore, J.S.; White, S.R. Polymers with Autonomous Life-cycle Control, Nature, 2016, 540, 363-370.

2. Robertson, I.D.; Yourdkhani, M.; Centellas, P.J.; Aw, J.; Ivanoff, D.G.; Goli, E.; Lloyd. E.M.; Dean, L.M.; Sottos, N.R.; Geubelle, P.H.; Moore, J.S.; White, S.R. Rapid Energy-efficient

Abstract: The biosynthesis of both fatty acids and polyketides involves a common reaction, the iterative carbon-carbon bond formation between acyl-thioesters and malonyl-thioesters. While fatty acids and polyketides are essential to society for a plethorea of reasons, how the underlying carbon-carbon bond forming reactions occur remains an open question. Malonyl-thioesters are akin to biochemical hot-potatoes, because they are prone to hydrolysis and decarboxylation. While these two high-energy reactions are exploited by nature for biosynthetic purpose, they plague the structural biologist. We developed molecules that look like malonyl-thioesters but are much more stable, thus we have chilled the hot-potato. These stable malonyl-thioester analogs have provided us with insight into the catalysis of three enzymes. Our preliminary studies with these malonyl-thioester analogs demonstrate that we will be able to generate insight into fatty acid and polyketide biosynthesis, paving the way for new routes to drugs, agrochemicals and biofuels.

The Yoshimoto research laboratory at UTSA harnesses the power of synthetic chemistry to solve challenging problems relevant to human health.

Artemisinin, one of the topics of the 2015 Nobel Prizes in Medicine, is an endoperoxide-containing sesquiterpenoid plant natural product used to treat malaria. The biosynthesis of the endoperoxide functional group, which gives the natural product its antimalarial activities, has been controversial. Using isotope-labeling strategies, we have elucidated the mechanism of the nonenzymatic endoperoxide forming cascade reaction that converts the precursor, dihydroartemisinic acid, to artemisinin in four steps: (i) first oxygen incorporation, (ii) C-C bond cleavage, (iii) second oxygen incorporation, (iv) and polycyclization to form artemisinin (1,2). Analogs of DHAA have been synthesized to probe endoperoxide formation, which led to the elucidation of the mechanism of the formation of the aromatic ring in serrulatene, an antibiotic plant natural product (3).

Secondly, human cytochrome P450 8B1, the oxysterol-12a-hydroxylase enzyme implicated in bile acid biosynthesis, is a therapeutic target to treat obesity. Preliminary studies involving the synthesis of a rationally designed inhibitor of P450 8B1 through the incorporation of a C12-pyridine in the steroid backbone, will be discussed (4).

1.         Varela, K., Arman, H. D., and Yoshimoto, F. K. (2020) Synthesis of [3,3-²H₂]-Dihydroartemisinic Acid to Measure the Rate of Nonenzymatic Conversion of Dihydroartemisinic Acid to Artemisinin. J. Nat. Prod. 83, 66-78

2.         Varela, K., Arman, H. D., and Yoshimoto, F. K. (2021) Synthesis of [15,15,15-²H₃]-Dihydroartemisinic Acid and Isotope Studies Support a Mixed Mechanism in the Endoperoxide Formation to Artemisinin J. Nat. Prod. 84, 1967-1984

3.         Varela, K., Al Mahmud, H., Arman, H. D., Martinez, L. R., Wakeman, C. A., and Yoshimoto, F. K. (2022) Autoxidation of a C2-Olefinated Dihydroartemisinic Acid Analogue to Form an Aromatic Ring: Application to Serrulatene Biosynthesis. J. Nat. Prod. 85, 951-962

4.         Chung, E., Offei, S. D., Jia, U. A., Estevez, J., Perez, Y., Arman, H. D., and Yoshimoto, F. K. (2022) A synthesis of a rationally designed inhibitor of cytochrome P450 8B1, a therapeutic target to treat obesity. Steroids 178, 108952